lshaderange(3G)						       lshaderange(3G)

NAME    [Toc]    [Back]

     lshaderange - sets	range of color indices used for	depth-cueing

C SPECIFICATION    [Toc]    [Back]

     void lshaderange(lowin, highin, znear, zfar)
     Colorindex	lowin, highin;
     long znear, zfar;

PARAMETERS    [Toc]    [Back]

     lowin    expects the low-intensity	color map index.

     highin   expects the high-intensity color map index.

     znear    expects the nearer screen	z, to which highin is mapped.

     zfar     expects the farther screen z, to which lowin is mapped.

DESCRIPTION    [Toc]    [Back]

     lshaderange sets the range	of color indices used for depth-cueing.	 The
     screen z range [znear, zfar] is mapped linearly into the color index
     range [highin, lowin].  Screen z values nearer than znear map to highin;
     screen z values farther than zfar map to lowin.

     The valid range for znear and zfar	depends	on the state of	the
     GLC_ZRANGEMAP compatibility mode (see glcompat).  If it is	0, the valid
     range depends on the graphics hardware.  When multisample is enabled, and
     multisample buffers exist in the current framebuffer configuration	in the
     current drawmode, the minimum is the value	returned by
     getgconfig(GC_MS_ZMIN) and	the maximum is the value returned by
     getgconfig(GC_MS_ZMAX).  Otherwise, the minimum is	the value returned by
     getgconfig(GC_ZMIN) and the maximum is the	value returned by
     getgconfig(GC_ZMAX).  If the state	of the GLC_ZRANGEMAP compatibility
     mode is 1,	the minimum is 0x0 and the maximum is 0x7FFFFF.	 The default
     is	lshaderange(0, 7, Zmin,	Zmax), where Zmin and Zmax are the values such
     that the full range supported by the graphics hardware is used.

     Znear and zfar should be chosen to	be consistent with the near and	far
     parameters	passed to lsetdepth. If	near < far, then znear should be less
     than zfar.	 If near > far,	then znear should be greater than zfar.	 In
     either case, the range [near, far]	should bound the range [znear, zfar].

SEE ALSO    [Toc]    [Back]

     depthcue, getgdesc, glcompat, lsetdepth

NOTE    [Toc]    [Back]

     When using	this routine, you should always	explicitly set the
     GLC_ZRANGEMAP mode	of glcompat because its	default	is different on
     different models.


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